The present invention relates to a non-flowable anhydrous topical antiperspirant composition comprising a first portion and a second portion contiguous with the first portion.
In WO 02/065998 there is described an antiperspirant product that includes two portions having different compositions. One embodiment includes a product having an application surface where one of the portions is in the form of a stripe that extends across the application surface approximately centrally through the other portion. One of the portions may be opaque and the other portion may be clear. Two ways of achieving clarity are described. In one, dibenzylidene sorbitol is used as the gelling agent to gel a polyhydric alcohol vehicle. In another, it is suggested to use a water-in-oil emulsion wherein the refractive index of the water phase is matched to the refractive index of the oil phase. In each of these systems, the antiperspirant salt is dissolved in the vehicle used in the clear portion.
In U.S. Pat. No. 4,120,948 there is described a two-phase antiperspirant stick composition having a shell and core structure. The core includes a particulate antiperspirant active suspended in a hydrophobic carrier gelled with a wax gelling agent. The shell includes a polyhydric alcohol gelled with a fatty acid soap, such as sodium stearate, or a fatty acid amide. The gel phase does not include antiperspirant salt. In DE 199 21 183 there is also described an antiperspirant stick composition having a shell and core structure. While the composition of the shell and core are said to be different, both include a hydrophobic liquid carrier, such as a silicone, that is solidified with a conventional gelling agent. One or both phases may include an antiperspirant salt suspended therein. There is no suggestion that either phase can be made translucent and, in the formulations exemplified, both phases are opaque.
In U.S. Pat. No. 5,384,117 there is described a clear anhydrous suspension-type antiperspirant stick composition in which the refractive index of the vehicle is matched to the refractive index of the antiperspirant salt. The gelling agent must also have a suitably matched refractive index. Examples of suitable gelling agents include polyethylene-vinyl acetate copolymer and polyethylene homopolymer. Similarly, in WO 01/058411 there is described a soft-solid antiperspirant composition in which the refractive index of the vehicle is approximately matched to the refractive index of the suspended antiperspirant salt, so that they differ by no more than 0.08. In this way, it is suggested that a ribbon of the composition dispensed through a narrow aperture will have a translucent appearance even though the gross formulation may be opaque.
In U.S. Pat. No. 5,972,319 and U.S. Pat. No. 6,361,766, there are described anhydrous antiperspirant compositions that contain a substantial amount of an emollient with a high refractive index to reduce whitening. The former suggests the use of emollients with a refractive index greater than about 1.446, while the latter suggests emollients with a refractive index greater than about 1.465.
It would be desirable to provide an antiperspirant composition having at least two contiguous portions, such as, for example, a striped antiperspirant product, wherein the composition has improved aesthetic properties, particularly an improved aesthetic appearance. In particular, it would be desirable to provide such a composition wherein one of the portions is translucent to transparent, but which does not require the use of a polyhydric alcohol/dibenzylidene sorbitol system or a water-in-oil emulsion system. In other words, it would be desirable to provide a translucent to transparent portion in which the carrier vehicle is a hydrophobic material such as a silicone or an organic oil.
In addition, it would be highly desirable to provide an antiperspirant composition having at least two contiguous portions wherein the portions are balanced compositionally so as to minimize migration of components from one portion to the other. Such migration, which readily occurs when one portion is compositionally different from the other portion (i.e. unbalanced), causes the product to become unstable and/or aesthetically unacceptable. For example, initial translucency or clarity can be lost over time.